FR2621689A1 - DEVICE FOR SEALING A CONTAINER FOR CONTAINING A PRESSURIZED FLUID - Google Patents

Abstract

The tightness control device is applied to a container 1 with a bottom 11 attached to a tubular body 10 by a rolled crimping bead 13. It comprises a head 4 for tight connection to a source of pressurized gas 49, a base 2 with a cylindrical side wall 20 where an O-ring 22 fits, and a flat bottom wall 21 where a circular seal 23 fits. The container body 10 bears on the seal 22, and the bead 13 on the seal 23, by the metal sheet where the bottom 11 is formed. Thus is delimited an enclosure 25 in communication with a manometric capsule 3. If there is a leak, the gas increases the pressure in the enclosure 25, from very low dead volume. If the pressure increase exceeds a threshold, a fault signal appears at 55.

Description

1 2621689

  Device for checking the tightness of a container for confining a fluid under pressure "The invention relates to a device for checking the tightness of a container intended to confine a pressurized fluid and comprising a tubular body and a bottom added along a circular bead in a plane perpendicular to the axis of the body, this device comprising a means of temporary sealed connection of the container to a source of pressurized gas, an enclosure o penetrates the container in sealed manner and provided with a manometric means, and additional means, coupled to manometric means, capable of detecting the increase in pressure in the enclosure resulting from an accidental leak of gas under

  pressure across the bead in a specified period.

  The containers whose tightness is to be checked in the context of the present invention are essentially aerosol sprays, the bottom of which, concave to withstand the pressure without compromising the vertical stability of the container, is added by rolled crimping bottom and body edges, with several folds. The seal is perfect by applying a rubber seal in the crimp cord,

applied in a pasty state.

  These sprayers further include a dome, at the end of the body opposite the bottom, generally attached by crimping also and having a central opening bordered o will be fixed, at a later stage of

  manufacturing, a spray valve.

  As these are mass-produced items, the tightness control process must be quick to

  implementation and lend itself to automation.

  The basic method consists in enclosing the container in a sealed enclosure, while the opening of the dome of the container receives a nozzle for sealing connection to a pressure source, with a seal. The enclosure

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  is connected to a pressure gauge. A gas pressure of a few bars is applied inside the container and the pressure prevailing in the enclosure outside the container is checked after a determined period of application of the pressure. If this pressure is significantly higher than the original pressure, it means that gas has passed from the inside of the container to the outside through

  a container wall leak.

  In practice, leaks occur during crimping. Furthermore, especially if the pressure inside the container is relatively high to apply significant forces to the crimps, we

  finds that very low flow leaks are very rare.

  Thus the containers which do not show a leakage rate under 9 bars of differential pressure greater than 0.5 cm3 / min (1.1 x 10-5 g / s in legal units) present practically a sufficient seal for their application.

destination.

  The current devices, operating on the process recalled above, react in about fifteen

  seconds at the minimum leak rate of 0.5 cm3 / min.

  It will be easily understood that the leakage control for mass production must be done on an automatic barrel machine with a multiplicity of positions, where the containers are gripped on a feed conveyor, loaded at a position, connected to the connection nozzle, enclosed in the enclosure, pressurized for a determined period, undergo a pressure measurement in the enclosure, are brought back to atmospheric pressure inside, extracted from the enclosure and finally, according to the results test, either unloaded on an evacuation conveyor if they are good, or discarded

if they flee.

  Due to the multiplicity of operations, and the time required to pressurize the containers, a high production rate requires a large machine.

  number of positions, expensive and cumbersome.

  Thus a typical testing machine (Borden Model AP-36-600) has a 36-position barrel with a

  footprint of approximately 3 m x 1.3 m x 2.7 m.

  It immediately appears that a substantial reduction in response time, the pressurization period after which a significant increase in the enclosure is detected in response to the typical minimum leak (0.5 cm3 / min) would be likely to reduce significantly the cost and size of a machine

test, with equal performance.

  One can hardly act on the sensitivity of the manometer, which must establish a sure discrimination between the increase in pressure which results from a leak and the random accidental variations of the pressure resulting from the variations in temperature, and of the maneuvers of the

  machine (especially rapid enclosure closure).

  The increase in pressure inside the containers would be ineffective, since one cannot exceed the values that the container can withstand without the risk of permanent deformation and deterioration. In addition, the leakage rate is practically proportional to the pressure difference between the ends of the leakage channel. By doubling the pressure in the container (18 bars instead of 9), we would double the leak rate, which would divide the response time by 2, i.e. a limited gain in sensitivity

  for an excessive increase in pressure.

  The third parameter on which we can act is the volume of the enclosure, the speed of pressure build-up in response to a defined leak being inversely proportional to the volume of the enclosure, remaining after

  introduction of the container, or dead volume.

  In practice, reducing the dead volume involves reducing the diameter of the enclosure. One is limited in this way by the need to leave a certain clearance between the container body and the lateral enclosure wall, both to avoid deterioration of poorly oriented axially containers and the piston effect of the body introduced at high speed into the enclosure. Finally the volume defined by the concave bottom and the volume at the height of the dome represent

incompressible dead volumes.

  The statistical analyzes of the sealing defects of the containers for pressurized fluid, in particular aerosol spray canisters, carried out by the Applicant have shown that more than 80% of the recorded defects related to the crimps, and in particular to the crimping of the bottom on the body. It therefore appeared that a tightness control of this crimping could

  constitute a reliable leak tightness test of the container.

  Thus, with the aim of making testing machines less expensive and bulky than conventional machines with performance, and in particular at least equal rates, the invention proposes a device for checking the tightness of a container intended to confine a fluid. under pressure and comprising a tubular body and a bottom added along a circular bead in a plane perpendicular to the axis of the body, device comprising a means of temporary sealed connection of the container to a source of gas under pressure, an enclosure o is introduced from tightly the container and provided with manometric means, and additional means, coupled to the manometric means, capable of detecting the increase in pressure in the enclosure resulting from an accidental leak of pressurized gas through the container in a specified period, characterized in that the enclosure is delimited, on the one hand by a base comprising a cylindrical side wall, and a flat and perpendicular bottom wall area at the side wall, and two elastomeric annular seals embedded respectively in the side wall and bottom, and on the other hand by the body and the bottom of the container coming to bear respectively on one or the other of the annular seals , with the cord arranged near the seals

annulars, between them.

  We understand that the enclosure thus has a minimum dead volume, so that we can identify the leak

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  minimum in two seconds from valve control

pressurization.

  In addition, the positioning of the container on the base requires only a short translation, rapid in comparison with the necessary translation greater than the length of the

body on conventional machines.

  Preferably, for a container whose bottom and body are crimped by rolling with several plies, the first ply, which defines the rest base of the container, relates to the

  gasket embedded in the back wall.

  Depending on whether the crimping is carried out by rolling towards the outside or inside, the cylindrical base wall is arranged outside or inside the crimping cord, and the seal embedded in this wall

  cylindrical bears on the body or on the bottom.

  Other features and benefits of

  the invention will moreover emerge from the description which will

  follow by way of example, with reference to the appended drawings in which: FIG. 1 is a sectional elevation of a device according to the invention, with a schematic indication of the connections; Figure 2 is a section of the base of the device of Figure 1, intended for a container with a crimp rolled outwards; Figure 3 is a section of a variant base, provided for a container with a crimp rolled inward; FIG. 4A is a section of a head for connection of the container to a pressure source, in the service position; FIG. 4B is a section of the head shown in FIG. 4A, in the insertion position; Figure 5 is a sectional view of a head variant for

  checking the tightness of the dome crimping.

  According to the embodiment chosen and shown in Figure 1, the device is intended to control the tightness of a container 1 as a whole intended to confine a pressurized fluid, such as an aerosol sprayer, and consisting of a tubular body 10, a concave bottom 11 attached to the body 10 by a crimping by rolling forming a bead 13 with several plies, and a dome 12 also reported by rolling crimping 14, and having

  a central opening bordered by a rolled rod 15.

  The tightness of the crimps 13 and 14 is perfect by filling with a rubber seal deposited in the pasty state,

in a classic way.

  The device comprises a base 2 as a whole comprising a lateral cylindrical wall 20 and a wall of

  flat bottom 21, perpendicular to the side wall 20.

  In the side wall 20 is embedded an O-ring in elastomer 22, while an annular seal in rectangular section 23, also in elastomer, is embedded in the bottom wall 21. As can be seen in FIG. 1, and better still in FIG. 2, the container 1 is inserted inside the cavity formed by the side walls 20 and bottom 21 of the base 2, so that the bottom crimping cord 13 bears on the seal 23 embedded in the bottom wall 21, while the body 10, coaxial with the cylindrical wall 20, is enclosed in the

  O-ring 22 embedded in this wall.

  As the crimping cord 13 is rolled outwards, the metal sheet which constitutes the bottom 11 is outside the cord up to the second ply, and rests on the seal 23 at the location of the first ply. An annular enclosure 25 is thus constituted, bounded on the one hand by the side walls 20 and bottom 21, and on the other hand by the lower part of the body 10 and the bottom sheet 11 between the first and second folds of the bead

crimping 13.

  Note that, if a leakage channel has formed in the crimping cord 13, it will necessarily open into the annular enclosure 25, because it will follow the direction of travel. The enclosure 25 is placed in communication with a manometric capsule 3 as a whole by means of a channel 24, constituted, as can be seen better in FIG. 2, of a succession of orthogonal bores blinded by screwed plugs . This channel 24 opens towards the enclosure 25 in the cylindrical wall 20, between the gasket 22 which is embedded therein and the connection to the bottom wall 21. Towards the manometric capsule 3, it opens at the center of a projection

frustoconical 29 of the base 2.

  As can best be seen in FIG. 2, the manometric capsule 3 comprises a deformable wall constituted by an elastic membrane 30 clamped at its periphery between the rim 28 of a recess 31 formed in the base 2 and a cylinder head 34. The membrane 30 comprises a circular wave which is housed between the flange 28 and the central frustoconical projection 29 machined in the base 2, so as to reduce the

  dead volume of the recess 31 under the membrane 30.

  In the center of the membrane 30 and on the side of the cylinder head

  34 is fixed a patch 32 of ferromagnetic material.

  In the axis of the capsule 3 and in front of the patch 32 is arranged an inductive sensor 33, with a connecting cord 35. It will be understood that a leak opening into the enclosure 25 will tend to repel the membrane 30 in s '' moving away from the base 2, so that the patch 32 approaches the inductive sensor 33, the latter emits a representative signal

  the volume of gas that has passed through the leak.

  If we refer to FIGS. 4A and 4B for the details of the connection head 4 which are not sufficiently clear in FIG. 1, it can be seen that the head 4 has a cup 40, at the end of a neck 41, this cup 40 coming to cover the dome 12 of the container 1 with a frustoconical imprint 40A, with a groove 40b for housing, centered, the rod 15 of

the central opening of the dome.

  The head 4 also comprises an axial tube 42, sliding in the cup neck 41 and connected to a source of compressed air 49, by means of a solenoid valve 48. The tube 42 penetrates axially into the container 1, and its end is provided with a flange 43, held by a hollow screw 43a engaged in the passage of the tube 42. This flange 43 has a flat periphery 43b, turned upwards, and a frustoconical core 43c which

  connects to the outside of the tube 42 upwards.

  On the tube 42 is threaded an elastically deformable tubular seal 44, taken between the neck 41 and the flange 43. Furthermore, this seal 44 is held, by a widening 44a, between the neck 41 and the internal edge of the

cup 40.

  For the establishment of the head 4 on the dome 12 of the container 1, the tube 42 is lowered (FIG. 4B) so that the flange 43 is below the seal 44. This seal 44

  can thus be inserted into the central opening of the dome 12.

  Thereafter, the tube 42 is retracted (FIG. 4A, FIG. 1) until the frustoconical core 43c is fully engaged in the seal 44, and the planar periphery 43b resting on the

lower edge of this joint 44.

  It is understood that thus the radial expansion of the seal 44 ensures its tight tightening on the rod 15 which borders the central opening of the dome 12, while the combination of the expansion by the core 43c and the pressure of the planar periphery 43b forces the part of the seal 44 which has entered the central opening of the dome 12 to form a radial bead which bears under the rod 15, in order to prevent the container 1 from being expelled under the effect

internal pressure.

  The operation of the device is controlled by

  additional means 5, which will be described below.

  To check the tightness of the crimping cord 13 of the container 1, this container is introduced into the base

  2, as has been said in connection with the description of

  this base, we put the head 4 with the tube 42 in the lowered position until covering the dome with the cup, then we retract the tube 42 as it was said above

  when describing head 4. Then a pilot

  central 50 sends a signal, on the one hand to the valve 48 to control its opening and thus to put the compressed air source 49 at approximately 9 bars in communication with the interior of the container 1, and on the other hand to a time delay 51,

set to approximately 2 seconds.

  As we said in the description of the capsule

  pressure gauge 3, if there is a leak in the cord 13, the membrane 30 and its ferromagnetic pad 32 gradually move towards the inductive sensor 33 which emits a

  signal in response, gradually increasing.

  This signal is sent to an input of a differential amplifier 52 mounted as an adjustable threshold comparator. If the signal emitted by the cap-eur 33 exceeds the threshold set by the potentiometer 53, the amplifier 52 emits a signal which is

  applied to a first entry of an AND 54 door.

  When the timer 51 arrives at the end of the period, it emits a signal which is applied to the second input of the AND gate 54, as well as to the central pilot 50 to complete

the test cycle.

  Thus, if the leakage rate of the cord 13 caused a switchover of the comparator 52 before the time delay 51 emits its end-of-period signal, on the appearance of this signal the two inputs of the AND gate 54 will be in state high, and a signal will appear on its output 55, meaning

that the cord 13 is leaking.

  On the other hand, if the comparator 52 has not switched over at the appearance of the signal for the end of the time delay period

  51, the cord 13 will be held waterproof.

  The variant shown in FIG. 3 relates to a container 1 in which the base 11 is attached to the body 1 by crimping rolled inwards, so that in the crimping cord 113 the metal sheet which constitutes the body 10 is located outside until

second fold.

  The base 102 then comprises a cylindrical side wall 120, and a flat bottom wall 121, perpendicular to the side wall 120. But here the side wall 120 is disposed inside the crimping cord 113, and therefore of the body 110 An elastomer O-ring 122 is embedded in the upper part of the side wall 120 so as to bear on the bottom 11, while the first fold of the crimping cord 113 bears on an annular seal 123 of rectangular section, also in

  elastomer, and embedded in the bottom wall 121.

  Thus, when the container 1 is placed on the base 102, a sealed enclosure 125 is defined, defined on the one hand by the side wall 120 and the bottom wall 121, and on the other hand by the body 10 and the bottom 11, the body 10 extending into the crimping cord 113, outside of the latter up to the second fold. As with a cord rolled outwards, an accidental escape channel

  thus opens into enclosure 125.

  A channel 124, which opens towards the enclosure 125 in the cylindrical side wall 120 between the seal which is embedded there and the connection with the bottom wall 121, places the enclosure 125 in communication with a capsule

  gauge 3 identical to the capsule in FIG. 2.

  It therefore suffices to replace the base 2 by the base 102 to transform the device for crimping cord rolled outwards 13 into a device for

  crimping cord 113 rolled inwards.

  If we consider FIG. 5, the connection head 4 which is represented there comprises, for its function of connection of the container 1 to a source of gas under pressure, the same elements as that which is represented in the figures

  1 and 4A, 4B, which bear the same references.

  But the cup 40 extends into a skirt 40j, towards the bottom of the container 1, beyond the rolled crimp 14 of the dome 12 on the body 10; an O-ring 62 is embedded in this skirt 40j, to come to bear on the body 10 in the vicinity of the crimping initiator 14. The latter is thus enclosed in an internal space 135 in the cup 40, between the tubular joint 44 and the O-ring 62. Cet.espace internal 135, cooperating with the walls of the container 1, constitutes an enclosure comparable to the enclosures 25 and 125 described above. A manometric capsule 63, of the same structure as the capsule 3 already described, communicates with the internal space 135 by a channel 40k. This capsule 63 comprises a flexible membrane 70 with a ferromagnetic pad 72, in axial extension of an inductive sensor 73. The signal emitted by the inductive sensor 73 will be

  treated like the one emitted by sensor 33.

  It will be appreciated that in this way it is possible to systematically check the tightness of the crimping of the dome, with the same sensitivity as the tightness of the crimping of the bottom, and without reducing the latter, since the enclosures 25, 125 and 135 are distinct. It will be appreciated that the device of the invention not only considerably reduces the cycle time, or active time, which goes from approximately 15 to 2 seconds, but also allows a significant reduction in the duration of the loading and unloading operations, by reducing the longitudinal stroke inserting the container into the enclosure and connecting the compressed air source, and

  by reducing the mass of moving parts.

  Of course, the invention is not limited to the examples described, but embraces the variants thereof.

within the scope of the claims.

  In particular, the additional means for sealing analysis which have only been described for their function can take any equivalent form of execution in its results, and can be incorporated or coupled with the means for controlling a

complete testing machine.

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Claims (11)

CLAIM $   1. Device for checking the tightness of a container (1) intended to confine a fluid under pressure and comprising a tubular body (10) and an attached base (11) along a circular bead (13, 113) in a perpendicular plane to the axis of the body (10), device comprising a temporary connection means (4) sealed from the container (1) to a source of pressurized gas (49), an enclosure (25, 125) o is sealed the container (1) and provided with a manometric means (3), and additional means (5), coupled to the manometric means, capable of detecting the increase in pressure in the enclosure (25, 125) resulting from a accidental leak of pressurized gas through the container (1) in a determined period, characterized in that the enclosure (25, 125) is delimited, on the one hand by a base (2, 102) having a cylindrical side wall (20, 120), and a flat bottom wall (21, 121) and perpendicular to the side wall (20, 120), and two annular seals (22, 122; 23, 123) in elastomer embedded parallel respectively in the side wall (20, 120) and bottom (21, 121), and on the other hand by the body (10) and the bottom (11) of the container (1) coming bear respectively on one or the other of the annular seals (22, 23; 122, 123), with the cord (13, 113) disposing of   proximity of the annular seals between them.   2. Device according to claim 1, for a container (1) where the cord (13, 113) was obtained by crimping rolled with several plies, with a rubber seal or the like, characterized in that the first ply of the crimping (13, 113) relates to the seal (23, 123) embedded in the bottom wall (21, 121) base (2).   3. Device according to claim 2, for a container (1) whose crimping cord (13) is rolled outward, characterized in that the cylindrical side wall (20) of base is arranged outside the cord (13 ) and the annular seal (22) embedded in this wall bears on the body (10).   4. Device according to claim 2, for a container (1) whose crimping cord (113) is rolled inward, characterized in that the cylindrical wall (120) of base is arranged internally to the cord (113) and the annular seal (122) embedded in this wall bears on the bottom (11).   5. Device according to any one of the claims   1 to 4, characterized in that the manometric means (3) consists of a disk-shaped capsule with an elastically deformable membrane wall (30), and a proximity sensor (33) sensitive to the axial displacement of the center of the membrane. 6. Device according to claim 5, characterized in that the proximity sensor (33) is of the inductive type and arranged aligned with the axis of the capsule (3), the membrane (30) carrying in its center a pellet (32 ) made of ferromagnetic material.   7. Device according to one of claims 5 and 6,   characterized in that the capsule (3) is formed by a recess (31) in the base (2), and is connected to the enclosure (25, 125) by a channel (24, 124) formed in the base (2, 102) and opening into the cylindrical wall (20, 120) between the seal (22, 122) which is embedded there and the connection to the flat wall (21, 121).   8. Device according to any one of the claims   1 to 7, for a container (1) comprising, at the end of the body (10) opposite the bottom (11), a dome (12) with a central opening bordered by a rod (15), characterized in that the connection means consists of a head (4) with a cup (40, 41) covering the dome (12), with an axial tube (42) connected to the source of pressurized gas (49), capable of sliding axially in the cup and terminated at its anterior end by a flange (43), and with an elastically deformable tubular joint (44) threaded on the tube (42) between the cup (40, 41) and the flange (43), capable of partially penetrate into the central opening of the dome (12), the retraction of the tube (42) relative to the cup (40, 41) thus causing a radial expansion of the tubular joint (44) which bears in a sealed manner on the rod ( 15) bordering the central opening dome (12).   9. Device according to claim 8, characterized in that the flange (43) is connected to the tube (42) on the side   of the tubular joint (44) by a truncated cone (43ú).   10. Device according to any one of   claims 8 and 9, where the dome (12) is fixed on the body   (10) by a rolled crimp (14), characterized in that the cup (40) extends in one piece, beyond the crimp (14) by a skirt (40j) with an O-ring (62) which carries on the body (10), a pressure means (63) being in communication with an interior space (135) in the cup (40), between the tubular seal (44) and the seal O-ring (62).   11. Device for checking the tightness of a container (1) intended to confine a pressurized fluid and comprising a tubular body (10), a bottom (11) and a dome (12) attached to the body (10) by a rolled crimp (14) and comprising a central opening bordered by a rod (15), device comprising a temporary connection means (4) sealed from the container (1) to a source of pressurized gas (49), an enclosure (135 ) o is tightly introduced the container (1) and provided with a pressure means (63) and additional means (5) coupled to the pressure means (63) capable of detecting the increase in pressure in the enclosure (135 ) resulting from an accidental leak of pressurized gas through the container in a determined period, characterized in that the connection means consists of a head (4), with a cup (40) covering the dome, with a axial tube (42) connected to the pressure source (49), and with an elastically deformable tubular joint (44) spun on the tube (42), taken in the cup (40) and able to partially penetrate into the central opening of the dome (12), and to carry in a sealed manner in the rod (15) by radial expansion, and in this that the cup (40), extended in one piece, beyond the crimping (14), by a skirt (40j) o an O-ring (62) which fits on the body (10) forms, between the tubular seal (44) and the O-ring (62), together with the container (1) an enclosure (135) in communication with the pressure gauge (63).